Temporal association between body weight and type 2 diabetes at the population level

Larger body size is strongly associated with type 2 diabetes, but the mechanisms linking the two remain uncertain. Proposed explanations include shared genetic susceptibility, effects of fat storage capacity and fat distribution, early-life influences, social and environmental factors, and reverse causation through insulin resistance affecting weight. We aim to clarify the timing and interplay of overweight, obesity, and type 2 diabetes at the population level. We analyze longitudinal data from the Health and Retirement Study, a nationally representative survey of older adults in the United States followed over time. The analytic sample consists of 7663 European-origin individuals with mean age at baseline as 57.24. We model transitions between weight status and diabetes status using Continuous Time Markov and Hidden Markov Chain models to evaluate how much alternative mechanisms beyond excess body weight account for observed associations. We show in this cohort, excess body weight is the factor most strongly associated with transitions into type 2 diabetes. Early-life conditions, genetic propensity to type 2 diabetes, and education play a secondary role by moderating the effects of excess body weight on type 2 diabetes risks. These findings indicate that, among older U.S. adults, excess body weight is the dominant correlate of T2D incidence in population transition patterns, while other proposed mechanisms contribute more modestly. This supports prevention strategies that prioritize maintaining healthy body weight to reduce type 2 diabetes risk. Overweight individuals are more likely to develop type 2 diabetes (T2D), but the mechanisms behind this association are not fully understood. This study examines whether patterns of T2D onset are explained primarily by excess body weight, or whether early-life conditions, genetic susceptibility, and education also account for the relationship. We use the Health and Retirement Study, a longitudinal survey following more than 20,000 U.S. older adults since 1992. Using repeated interviews, we track changes in weight status and diabetes status over time and compare how well different explanations align with observed transitions. Excess body weight shows the strongest association with subsequent T2D, while early-life factors, genetic propensity, and education contribute more modestly, mainly by shaping the strength of the weight–T2D link. Huangfu et al. use longitudinal Health and Retirement Study data and Markov and hidden Markov models to examine the association between obesity and T2D after age 45. They find excess weight strongly predicts diabetes onset, while genetic risk, early-life factors, and education play smaller roles in the association between obesity and T2D.